Myeloma protein

A myeloma protein is an abnormal immunoglobulin fragment, such as an immunoglobulin light chain, that is produced in excess by an abnormal monoclonal proliferation of plasma cells, typically in multiple myeloma. Other terms for such a protein are M protein, M component, M spike, spike protein, or paraprotein. This proliferation of the myeloma protein has several deleterious effects on the body, including impaired immune function, abnormally high blood viscosity ('thickness' of the blood), and kidney damage.The concept and the term paraprotein were introduced by the Berlin pathologist Dr Kurt Apitz in 1940, then the senior physician of the pathological institute at the Charité hospital.Myeloma is a malignancy of plasma cells. Plasma cells produce immunoglobulins, which are commonly called antibodies. There are thousands of different antibodies, each consisting of pairs of heavy and light chains. Antibodies are typically grouped into five types: IgA, IgD, IgE, IgG, and IgM. When someone has myeloma, a malignant clone, a rogue plasma cell, reproduces in an uncontrolled fashion, resulting in overproduction of the specific antibody the original cell was generated to produce. Each type of antibody has a different number of light chain and heavy chain pairs. As a result, there is a characteristic normal distribution of these antibodies in the blood by molecular weight.Blood serum paraprotein levels of more than 3 g/l is diagnostic of smouldering myeloma, an intermediate in a spectrum of step-wise progressive diseases termed plasma cell dyscrasias. Elevated paraprotein level (above 30 g/l) in conjunction with end organ damage (elevated calcium, renal failure, anemia, or bone lesions) or other biomarkers of malignancy, is diagnostic of multiple myeloma, according to the diagnostic criteria of the International Myeloma Working Group, which were updated in 2014. Detection of paraprotein in serum of less than 30 g/l is classified as monoclonal gammopathy of undetermined significance in cases where clonal plasma cells constitute less than 10% on bone marrow biopsy and there is no myeloma-related organ or tissue impairment.